Light-emitting device

ABSTRACT

Disclosed is a light-emitting device comprising a light-emitting stack having a length, a width, a first semiconductor layer, an active layer on the first semiconductor layer, and a second semiconductor layer on the active layer, wherein the first semiconductor layer, the active layer, and the second semiconductor layer are stacked in a stacking direction. A first electrode is coupled to the first semiconductor layer and extended in a direction parallel to the stacking direction and a second electrode is coupled to the second semiconductor layer and extended in a direction parallel to the stacking direction. A dielectric layer is disposed between the first electrode and the second electrode.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication Ser. No. 14/579,807, filed on Dec. 22, 2014, which is acontinuation application of U.S. patent application Ser. No. 13/851,997,now U.S. Pat. No. 8,916,884, filed on Mar. 28, 2013, which claimspriority to Taiwan Patent Document No. 101111652, filed on Mar. 30, 2012with the Taiwan Patent Office, of which disclosures are herebyincorporated by reference in their entireties.

TECHNICAL FIELD

The application relates to a light-emitting device, and more particularto a light-emitting device with an enhanced light extraction.

DESCRIPTION OF BACKGROUND ART

FIGS. 1A and 1B show the schematic diagrams of a known light-emittingdiode. FIG. 1A is the top view, and FIG. 1B is the cross-sectional view.For a known light-emitting diode, a light-emitting stack 101 is formedon the substrate 111. The light-emitting stack 101 comprises a firstconductivity type semiconductor layer 101 a, an active layer 101 b, anda second conductivity type semiconductor layer 101 c The firstconductivity type semiconductor layer 101 a and the second conductivitytype semiconductor layer 101 c are of different conductivity type. Forexample, the first conductivity type semiconductor layer 101 a is ann-type semiconductor layer, and the second conductivity typesemiconductor layer 101 c is a p-type semiconductor layer. A firstelectrode 104 and a second electrode 105 are disposed on the firstconductivity type semiconductor layer 101 a and the second conductivitytype semiconductor layer 101 c respectively to conduct the electriccurrent. In addition, a transparent conductive layer 103 is disposed onthe second conductivity type semiconductor layer 101 c as an ohmiccontact layer. Metal and a transparent conductive material can beapplied to the light-emitting diode as an ohmic contact material atpresent. However, metal has the advantage of good current conductingwhile it has the disadvantage of light absorbing. And the transparentconductive material has an advantage of light transmittance while it isinferior to the metal in the current conducting. Currently, most of thesolutions are using the transparent conductive layer 103 for ohmiccontact together with the metal lines as the extending electrodes 105 ato conduct the electric current. The design of adopting the metal linesas the extending electrodes 105 a provides good current conducting butincreases the shielding because of the metal material, which results ina loss of light intensity.

SUMMARY OF THE DISCLOSURE

Disclosed is a light-emitting device comprising a light-emitting stackhaving a length, a width, a first conductivity type semiconductor layer,an active layer on the first conductivity type semiconductor layer, anda second conductivity type semiconductor layer on the active layer,wherein the first conductivity type semiconductor layer, the activelayer, and the second conductivity type semiconductor layer are stackedin a stacking direction. A first electrode is coupled to the firstconductivity type semiconductor layer and extended in a directionparallel to the stacking direction and a second electrode is coupled tothe second conductivity type semiconductor layer and extended in adirection parallel to the stacking direction. A dielectric layer isdisposed between the first electrode and the second electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates the top view of the light-emitting diode known inthe prior art.

FIG. 1B illustrates the cross-sectional view of the light-emitting diodeknown in the prior art.

FIGS. 2A to 2F illustrate the forming method and the structure of thelight-emitting diode in accordance with first embodiment of the presentapplication.

FIGS. 3A to 3E illustrate the forming method and the structure of thelight-emitting diode in accordance with second embodiment of the presentapplication.

FIGS. 4A to 4D illustrate the forming method and the structure of thelight-emitting diode in accordance with third embodiment of the presentapplication.

FIG. 5 illustrates a light-emitting apparatus which applies thelight-emitting devices in accordance with the embodiments of the presentapplication.

FIGS. 6A to 6I illustrate the forming method and the structure of thelight-emitting diode in accordance with fourth embodiment of the presentapplication.

FIG. 7 illustrates the structure of the light-emitting diode inaccordance with fifth embodiment of the present application.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 2 shows the first embodiment of the present application. As shownin FIG. 2A, a first light-emitting stack 201 is firstly formed on asubstrate 211, wherein the first light-emitting stack 201 comprises afirst conductivity type semiconductor layer 201 a, an active layer 201b, and a second conductivity type semiconductor layer 201 c from thebottom to the top. The first conductivity type semiconductor layer 201 aand the second conductivity type semiconductor layer 201 c are ofdifferent conductivity type. For example, the first conductivity typesemiconductor layer 201 a is an n-type semiconductor layer, and thesecond conductivity type semiconductor layer 201 c is a p-typesemiconductor layer. Then a part of light-emitting stack 201 is takenoff to be used for following processes by a method, for example, theEpitaxy Lift-Off (ELO) method. As shown in FIG. 2A, firstly, theseparating lines 213 and 213′ are formed between the part to be takenoff (part C) and the adjacent remaining parts (part L and part R)respectively by laser cutting or a method of lithography and etching tofacilitate the following lift-off step. Then a temporary substrate 212,such as glass, is provided to be bonded to the part C to be taken off.The bonding method may be forming a bonding material (not shown) at thebonding interface 215 (shown in FIG. 2B), and the temporary substrate212 and the substrate 211 are heated and pressurized for bonding. Thebonding material may be a conductive material or a non-conductivematerial. The conductive material comprises metal or metal alloy, suchas gold, silver, and tin, or alloy thereof. The non-conductive materialcomprises polyimide (PI), benzocyclobutene (BCB), perfluorocyclobutane(PFCB), epoxy resin (Epoxy), and other organic bonding material. Thebonding method is well known in this field of the art so the details arenot illustrated. After the bonding step, as shown in FIG. 2B, a laserirradiation 214 is employed at the interface of the part C to be usedand the substrate 211, and at the same time the part C to be used islifted upward through its bonding to the temporary substrate 212 and istaken off. As shown in FIG. 2B, the taken-off light-emitting stack 201has a length L and a width W, and the x-axis illustrated in the figureis parallel to the length L, while the y-axis is parallel to the widthW.

Then, as shown in FIG. 2C, a permanent substrate 206 is provided. Thepermanent substrate 206 may be a conductive substrate or anon-conductive substrate. The conductive substrate may be a substrate ofa semiconductor material (such as silicon), silicon carbide, or metal.The non-conductive substrate may be, for example, a substrate ofsapphire (Al₂O₃), glass, or ceramic material. A silicon (Si) substrate206 b, which is commonly used in the industry, is used in the presentembodiment. Because a horizontal structure is illustrated in the presentembodiment, a dielectric layer 206 a, such as silicon oxide, is firstlyformed on the Si substrate 206 b to form the permanent substrate 206 inthe present embodiment. A conductive layer 202 is subsequently formed onthe permanent substrate 206, and the width W′ of the conductive layer202 is larger than the width W of the aforementioned taken-offlight-emitting stack 201. The conductive layer 202 may be metalmaterial, metal oxide, or a stack of both. The metal material may beindium (In), gold (Au), titanium (Ti), platinum (Pt), aluminum (Al), orsilver (Ag), or the metal alloy of the above metal materials, or thestack of the above metal materials. The metal oxide may be indium tinoxide (ITO). And then the taken-off light-emitting stack 201 is bondedto the conductive layer 202. For example, a bonding layer 208 is firstlyformed on the light-emitting stack 201, and then the taken-offlight-emitting stack 201 is bonded to the conductive layer 202 throughthe bonding layer 208. In one embodiment, the bonding layer 208comprises indium tin oxide (ITO), and the conductive layer 202 is astack of titanium (Ti)/gold (Au)/silver (Ag)/indium tin oxide (ITO). Inaddition, the bonding layer 208 may comprise a reflective metal to actas a reflecting mirror at the same time. One example is that a stack ofsilver (Ag)/titanium (Ti)/platinum (Pt)/gold (Au) is formed on thelight-emitting stack 201 as the bonding layer 208, and the conductivelayer 202 is a stack of titanium (Ti)/gold (Au)/indium (In) from thebottom to the top. Similarly, bonding can be done through heating andpressuring. And as the laser irradiation method illustrated above, byemploying a laser irradiating at the interface of the light-emittingstack 201 and the temporary substrate 212, the temporary substrate 212is removed. As shown in FIG. 2D, the conductive layer 202 is under thelight-emitting stack 201, or more specifically, under the firstconductivity type semiconductor layer 201 a thereof (not shown in thisfigure, please refer to FIG. 2A). Since the width W′ of the conductivelayer 202 is larger than the width W of the light-emitting stack 201,the conductive layer 202 can be deemed to be composed of a firstoverlapping portion 202 a and a first extending portion 202 b, whereinthe first overlapping portion 202 a overlaps the first conductivity typesemiconductor layer 201 a while the first extending portion 202 b doesnot overlap the first conductivity type semiconductor layer 201 a. Thefirst extending portion 202 b extends in a first direction (+ydirection) which is in parallel to the width direction. Next, as shownin the figure, a dielectric layer 207 is formed at the sidewalls of thelight-emitting stack 201 and the conductive layer 202 by processes suchas a Chemical Vapor Deposition (CVD) method or an Electron-Gun (E-gun)method along with processes such as a method of lithography and etchingor a photoresist Lift-Off method. The material of the dielectric layer207 may be silicon oxide (SiO₂), silicon nitride (SiN_(x)), or aluminumoxide (Al₂O₃).

Next, as shown in FIG. 2E, a transparent conductive layer 203 is formedon the light-emitting stack 201, or more specifically, on the secondconductivity type semiconductor layer 201 c thereof (not shown in thisfigure, please refer to FIG. 2A). Similarly, since the transparentconductive layer 203 comprises a width larger than the width of thesecond conductivity type semiconductor layer 201 c, the transparentconductive layer 203 can be deemed to be composed of a secondoverlapping portion 203 a and a second extending portion 203 b, whereinthe second overlapping portion 203 a overlaps the second conductivitytype semiconductor layer 201 c while the second extending portion 203 bdoes not overlap the second conductivity type semiconductor layer 201 c,and the second extending portion 203 b extends in a second direction (−ydirection) which is in parallel to the width direction, and the seconddirection (−y direction) is opposite to the first direction (+ydirection). The transparent conductive layer 203 may be metal oxide or athin metal of a thickness less than 500 Å. Metal oxide may be indium tinoxide (ITO), aluminum zinc oxide (AZO), cadmium tin oxide, antimony tinoxide, zinc oxide (ZnO), indium zinc oxide (IZO), zinc tin oxide (ZTO),or a group comprising the above materials. The thin metal may bealuminum, gold, platinum, zinc, silver, nickel, germanium, indium, ortin, or the metal alloy of the above metal materials. Finally, as shownin FIG. 2F, a first electrode 204 is formed on the first extendingportion 202 b, and a second electrode 205 is formed on the secondextending portion 203 b. It is noted that, as shown in the figure, thefirst electrode 204 is substantially joined with only the firstextending portion 202 b of the conductive layer 202 or a portionthereof, and the second electrode 205 is substantially joined with onlythe second extending portion 203 b of the transparent conductive layer203 or a portion thereof. In other words, there is no any part of thesecond electrode 205 or any commonly known extending electrode disposedon the second overlapping portion 203 a, which is the portion of thetransparent conductive layer 203 overlapping the second conductivitytype semiconductor layer 201 c. Therefore, there is no light intensityloss caused by the shielding of the metal material. Accordingly, in thepresent embodiment, the current conduction into the light-emitting stack201 in the direction parallel to the width direction of thelight-emitting stack 201, i.e., y direction, is done substantiallythrough the second overlapping portion 203 a of the transparentconductive layer 203. Taking the transparent conductive layer 203comprising indium tin oxide as an example, the thickness is generally ina range of from 50 nm to 1 μm. In the case of a thickness of 120 nmwhich is commonly used, the distance for current conduction (or chargetransfer) is about 30 μm to 100 μm (i.e., 0.1 mm). Therefore, the widthW of the light-emitting stack 201 can be designed to be about 100 μm(i.e., 0.1 mm) in this embodiment, and for a light-emitting stack having42 mil*42 mil (or about 1 mm*1 mm, or 1 mm²) area which is common forthe commercial specification, the length of the light-emitting stack 201in this embodiment can be lengthened so as to provide the samelight-emitting area. In this way, the current conduction is achieved byusing the excellent current conduction characteristic of metal materialof the second electrode 205, and then the transparent conductive layer203 with high transparency conducts current to the light-emitting stack201. Accordingly, the current is uniformly conducted while the shieldingby the metal material of the electrode or extending electrode on thelight-emitting area is avoided. The length L of the light-emitting stack201 can be about 10 mm (1 mm²/0.1 mm=10 mm), and the ratio of the lengthL to the width W is 10 mm:0.1 mm, or 100:1. Generally, the thicker thethickness of the indium tin oxide of the transparent conductive layer203 is, the longer the distance for current conduction is, so the widthW can be designed to be larger than the width in the above example. Thedesign parameters, such as the light-emitting area, can also beadjusted. For example, when the light-emitting area is adjusted to besmaller than that in the above example, the length L can becorrespondingly designed to a smaller value than the one in the aboveexample. For example, when the width W is enlarged to 2 times of the onein the above example, and the length L is reduced to 1/10 of the one inthe above example, a ratio of the length L to the width W of thelight-emitting stack 201 greater than about 5:1 can achieve the abovepurposes.

FIGS. 3A to 3E show the second embodiment in the present application.The second embodiment is a modification of the first embodiment above.In the first embodiment, as shown in FIG. 2F, the first electrode 204 isdisposed over the first extending portion 202 b, and the secondelectrode 205 is disposed over the second extending portion 203 b. Inthe second embodiment, as shown in FIG. 3E, the first electrode 304 isdisposed under the first extending portion 302 b, and the secondelectrode 305 is disposed under the second extending portion 303 b. Inaddition, the permanent substrate 206 composed of the silicon substrate206 a and the dielectric layer 206 b thereon in the first embodiment isreplaced by glass as the permanent substrate 306 in the secondembodiment. Apart from the above, the second embodiment is substantiallythe same as the first embodiment. Therefore, with the reference to theprocesses illustrated in FIGS. 2A to 2E in the first embodiment, astructure in FIG. 3A which is similar to FIG. 2E can be obtained. Thestructure comprises a permanent substrate 306, a conductive layer 302, alight-emitting stack 301, a dielectric layer 307, and the transparentconductive layer 303. Next, as shown in FIG. 3B, the structure in FIG.3A is bonded to a temporary substrate 362 with a bonding material 361 inorder to facilitate the formation of the electrodes in the followingsteps. And then, as shown in FIG. 3C, by forming a protective layer (notshown), such as a photoresist, on the permanent substrate 306, butexposing the parts 306 a, 306 b where the electrodes are to be formed,and by using a method of lithography and etching or a sandblastingmethod, or a combination of both, the parts 306 a, 306 b of thepermanent substrate 306 for forming the electrodes are removed. Inaddition, the part 307 a where the dielectric layer 307 joins the part306 a for forming electrode is also removed. With the above processes, aportion of the conductive layer 302 and a portion of the transparentconductive layer 303 are exposed so that the first electrode 304 andsecond electrode 305 are formed thereon in the following steps, as shownin FIG. 3D. In some applications, the bonding material 361 and thetemporary substrate 362 can be reserved. However, in the presentembodiment, the laser irradiation as illustrated previously can beemployed to the bonding material 361 or an etching method can be used toremove the bonding material 361 and the temporary substrate 362, and astructure in accordance with the second embodiment is formed as shown inFIG. 3E. Similarly, in the present embodiment, the first electrode 304joins with only the first extending portion 302 b of the conductivelayer 302 substantially or a portion of the first extending portion 302b, and the second electrode 305 joins with only the second extendingportion 303 b of the transparent conductive layer 303 substantially or aportion of the second extending portion 303 b. In other words, there isno any part of the second electrode 305 or any extending electrodedisposed on the second overlapping portion 303 a of the transparentconductive layer 303. And therefore there is no light intensity losscaused by the shielding of the metal material.

FIGS. 4A to 4D show the third embodiment of the present application. Thethird embodiment is also a modification of the first embodiment. In thefirst embodiment, as shown in FIG. 2F, the first electrode 204 isdisposed over the first extending portion 202 b, and the secondelectrode 205 is disposed over the second extending portion 203 b. Inthe third embodiment, as shown in FIG. 4C, the first electrode 404 isdisposed under the first extending portion 402 b, and the secondelectrode 405 is disposed over the second extending portion 403 b. Inaddition, the permanent substrate 206 composed of the silicon substrate206 b and the dielectric layer 206 a thereon in the first embodiment isreplaced by a transparent material as the permanent substrate 406 in thethird embodiment. The transparent material may be a dielectric material,such as glass. Apart from the above, the third embodiment issubstantially the same as the first embodiment. Therefore, with thereference to the processes illustrated in FIGS. 2A to 2E in the firstembodiment, a structure in FIG. 4A which is similar to FIG. 2E can beobtained. The structure comprises a permanent substrate 406 comprisingglass, a conductive layer 402, a light-emitting stack 401, a dielectriclayer 407, and the transparent conductive layer 403. It is noted thatsince indium tin oxide (ITO) is adopted as the conductive layer 402 ofthe present embodiment, the method for bonding the conductive layer 402to the light-emitting stack 401 has been illustrated in the firstembodiment. That is, a bonding layer 408, for example, indium tin oxide(ITO) is first formed on the light-emitting stack 401 and then thelight-emitting stack 401 is bonded to the conductive layer 402 throughthe bonding layer 408. It is noted that the conductive layer 402 coversentire light-emitting stack 401, and therefore when compared with thefirst embodiment, the conductive layer 402 can be deemed to furthercomprise a third extending portion 402 c in addition to the firstoverlapping portion 402 a and the first extending portion 402 b.Similarly, the transparent conductive layer 403 can be deemed to furthercomprise the second overlapping portion 403 a, the second extendingportion 403 b, and a fourth extending portion 403 c. And in the presentembodiment, the first extending portion 402 b and the second extendingportion 403 b extend in the same direction (−y direction), and the thirdextending portion 402 c and the fourth extending portion 403 c extend inthe same direction (+y direction).

Next, as shown in FIG. 4B, another transparent material, for example, atransparent substrate 462 of a dielectric material like glass isprovided. After a transparent conductive layer 403′ formed on thetransparent substrate 462, the transparent substrate 462 is bonded tothe structure in FIG. 4A. The transparent conductive layer 403′comprising indium tin oxide (ITO) is bonded to the transparentconductive layer 403 which also comprises the indium tin oxide (ITO).Next, as shown in FIG. 4C, by using a method of lithography and etchingor a sandblasting method, or a combination of both, a part of thepermanent substrate 406 and a part of the transparent substrate 462 areremoved to expose a part of the conductive layer 402 and a part of thetransparent conductive layer 403′. And then a first electrode 404 isformed under the first extending portion 402 b, and a second electrode405 is formed over the transparent conductive layer 403′ to form thecompleted third embodiment.

As shown in FIG. 4C, in the third embodiment, the first electrode 404has a first surface (the one which contacts the PP′ plane) which isperpendicular to the first extending portion 402 b, and the secondelectrode 405 has a second surface (the one which contacts the PP′plane) which is perpendicular to the second extending portion 403 b. Thefirst surface and second surface are substantially coplanar on the PP′plane. Therefore, the first surface and the second surface can be bondedto a carrier (not shown) having the PP′ plane as the carrier surface. Inapplications, the light-emitting device may be rotated by 90 degrees, asshown in FIG. 4D, so the light emitted by the light-emitting stack 401is emitted to multiple directions, wherein the permanent substrate 406,the transparent substrate 462, and the dielectric layer 407 are alltransparent materials for light extraction. An advantage ofOmni-direction lighting is included.

As shown in FIG. 5 , the light-emitting devices illustrated in the abovethree embodiments may be further connected to and combined with otherelements to form a light-emitting apparatus 500. The light-emittingapparatus 500 comprises a sub-mount 510 having one circuit 511, 512,513, 514; and one light-emitting device disposed on the sub-mount 510.There are three light-emitting devices 501, 502, 503 on the sub-mount510 in the present embodiment, wherein the light-emitting devices 501,502, 503 may be any one of the light-emitting devices illustrated in theabove three embodiments, and the electrodes of the light-emittingdevices 501, 502, 503 may be soldered to the circuit 511, 512, 513, 514of the sub-mount 510 with a solder (not shown). For example, the twoelectrodes 501 a, 501 b of the light-emitting device 501 arerespectively bonded to the circuit 511, 512; the two electrodes 502 a,502 b of the light-emitting device 502 are respectively bonded to thecircuit 512, 513; the two electrodes 503 a, 503 b of the light-emittingdevice 503 are respectively bonded to the circuit 513, 514. In this waythe light-emitting devices 501, 502, 503 may be fixed to the sub-mount510, and form a serial connection (as the present embodiment shows) or aparallel connection or both serial and parallel connection. And anexternal power supply is provided to the device 500 through theconductive material structure 521, 522, such as gold wires or copperwires. The sub-mount 510 may be ceramic, glass, glass fiber, orbakelite.

In addition to the above embodiments, it is also possible to make theelectrodes and the extending electrode which are set on thelight-emitting stack in the prior art substantially not to cover thelight-emitting stack by the way of processing, while leaving only asmall area for electrical connection so the light-shielding effect isminimized and the metal shading problem is alleviated. Itsimplementation is illustrated as the fourth embodiment of the presentinvention shown in FIGS. 6A to 6I. In FIG. 6A, a light-emitting stack601 comprising a first conductivity type semiconductor layer 601 a, anactive layer 601 b, and second conductivity type semiconductor layer 601c is formed on the substrate 611. Before the light-emitting stack 601 isformed, an intermediate layer structure 681, for example a buffer layeris optionally formed. Then a contact layer 604 is formed on thelight-emitting stack 601. The contact layer 604 may be a transparentconductive oxide or a metal; the transparent conductive oxide may beindium tin oxide (ITO), aluminum zinc oxide (AZO), cadmium tin oxide,antimony tin oxide, zinc oxide (ZnO), indium zinc oxide (IZO), or zinctin oxide (ZTO) or the group composed of these materials; the metal maybe aluminum, gold, platinum, zinc, silver, nickel, germanium, indium,tin, beryllium, platinum, or rhodium or the metal alloy of these metalmaterials. When the metal selected is highly reflective metal, such asaluminum and silver, the metal can function as a reflecting mirror; or areflection structure (not shown), such as a Distributed Bragg Reflector(DBR) or an Omni-Directional Reflector (ODR) may be alternatively set onthe contact layer 604 in order to provide the reflection function. Next,by the method of lithography and etching, portions of the contact layer604 are removed to form removed contact layer regions 604 a. Then, asshown in FIG. 6B, a protective layer 659 is formed on the contact layer604, and the protective layer 659 fills the removed contact layerregions 604 a. As the figure shows, two regions of the contact layer 604which are reserved for electrodes, i.e. the first electrode 604′ and thesecond electrode 604″, are not covered by the protective layer 659. Asshown in FIG. 6C, the structure in FIG. 6B is bonded to a temporarysubstrate 682 by a bonding material 683 for the subsequent processes.Next, as the laser irradiation method illustrated previously, a laser(not shown) is employed to irradiate on the interface of the substrate611 and the intermediate layer structure 681 to remove the substrate611. The removal of the substrate 611 can also be done by an etchingmethod. The structure after the removal of the substrate 611 is shown inFIG. 6D.

As FIG. 6E shows, by the method of lithography and etching, portions ofthe intermediate layer structure 681 and the light-emitting stack 601are removed to form isolation areas 684 and expose the contact layer 604below and the protective layer 659 which fills the removed contact layerregions 604 a as illustrated previously. As a result, the whole largearea of the light-emitting stack 601 is divided into a plurality oflight-emitting units with relatively smaller area. As in the presentembodiment shows, the light-emitting stack 601 is divided into twolight-emitting units with relatively smaller area; each of whichisolated from each other by the isolation area 684. Next, as shown inFIG. 6F, a dielectric layer 685, such as silicon oxide (SiO₂), siliconnitride (SiN_(x)), or aluminum oxide (Al₂O₃), is formed on the structureof FIG. 6E. And then portions of the dielectric layer 685 is removed bya method of lithography and etching to form electrical connection region685 a and expose the contact layer 604 below (in some circumstances, theaforementioned protective layer 659 which fills the removed contactlayer regions 604 a may also be exposed). The surface of theintermediate layer structure 681 is also substantially completelyexposed to extract the light emitted by the light-emitting stack 601.The light-emitting units are electrically isolated from each other bythe dielectric layer 685, and the conductive layer which is filled intothe electrical connection region 685 a in following steps makes thelight-emitting units electrically connected in series, in parallel, orin both series and parallel. As shown in FIG. 6G, a conductive layer686, such as a metal material like aluminum, gold, platinum, zinc,silver, nickel, germanium, indium, and tin, or the metal alloy of theabove metal materials is formed on the structure of FIG. 6F, and then aportion of the conductive layer 686 is removed by lithography andetching to form the aforementioned electrical connection. A serialconnection case is shown in the present embodiment. The conductive layer686 is filled into the electrical connection region 685 a and iselectrically connected to the exposed contact layer 604 (through one endthereof), while the other end (i.e., 605) of the conductive layer 686 isin contact with a part of the surface of the intermediate layerstructure 681. In addition, as shown in FIG. 6G, before the conductivelayer 686 is formed, a transparent conductive layer 603 may also beoptionally formed on the intermediate layer structure 681, and thereforein the present embodiment the other end (i.e., 605) of the conductivelayer 686 is in contact with the surface of the transparent conductivelayer 603. As described above, since the large area of thelight-emitting stack 601 is divided into a plurality of light-emittingunits with relatively smaller area, the width (W) of each light-emittingunit becomes smaller and falls into a distance range for effectivecurrent conduction. When the transparent conductive layer 603 exists, noextending electrode is needed for the light-emitting units, and the end(i.e., 605) of the conductive layer 686 which electrically contacts thelight-emitting stack 601 can be small so that current is uniformlyconducted while the shielding by the metal material of the electrode orextending electrode upon the light-emitting area is avoided. Similarly,a common suitable light-emitting area may be obtained by appropriatelydetermining the aspect ratio of each of the light-emitting units asprevious illustration. For example, the aspect ratio may be aboutgreater than 5:1 as illustrated in the aforementioned light-emittingstack. In addition, since this embodiment may be implemented in varioustypes of serial and parallel connection, a light-emitting area forcommercial specifications may be obtained by connecting an appropriatenumber of light-emitting units without adjusting the aspect ratio ofeach of the light-emitting units. Next, as shown in FIG. 6H, thestructure in FIG. 6F is bonded to a transparent substrate 606 comprisinga transparent material like glass by a transparent bonding material 607,such as polyimide (PI), benzocyclobutene (BCB), or perfluorocyclobutane(PFCB) and serves as a light extraction surface. Next, as shown in FIG.6I, the temporary substrate 682 and the bonding material 683 are removedby a method, such as etching, to complete the present embodiment. Theconnection for the light-emitting units is as described above, and theexternal power supply can be provided through the aforementioned firstelectrode 604′ and the second electrode 604″. The above embodimentillustrates the case of a serial connection, and the fifth embodimentshown in FIG. 7 which illustrates the case of a parallel connection canbe obtained by the person of ordinary skill in the art by simplyadjusting the processes illustrated in FIGS. 6A to 6I. The adjustmentsinclude adjustments of removed contact layer regions 604 a in FIG. 6A,adjustments of the formation of isolation area 684 in FIG. 6E, andadjustment of the removal of the conductive layer 686 in FIG. 6G.Accordingly, the first digit of the label code of FIG. 6I is changedfrom “6” to “7” in FIG. 7 . For example, the label code 606 is thetransparent substrate 606, so the label code 706 is also a transparentsubstrate by analogy. However, it is noted that the middle part of thecontact layer 704 (i.e., the part of the contact layer 704 which iselectrically connected to the first conductivity type semiconductorlayer 701 a through the conductive layer 786) is the first electrode forthe serial connection, and the two side parts of the contact layer 704(i.e., the parts of the contact layer 704 which are disposed below andelectrically connected to the second conductivity type semiconductorlayer 701 c) are the second electrode for the serial connection (the twoside parts of the contact layer 704 can be connected through their topview layout). The two light-emitting units are therefore in parallelconnection.

The above-mentioned embodiments are only examples to illustrate thetheory of the present invention and its effect, rather than be used tolimit the present invention. Other alternatives and modifications may bemade by a person of ordinary skill in the art of the present applicationwithout escaping the spirit and scope of the application, and are withinthe scope of the present application.

What is claimed is:
 1. A light-emitting device, comprising: aninsulative substrate; a light-emitting stack formed on the insulativesubstrate, and having an upper surface, a lower surface opposite to theupper surface, and a first sidewall arranged between the upper surfaceand the lower surface; a first upper conductive layer covering entiretyof the upper surface and extending beyond the light-emitting stack alonga first direction and without extending along a second direction whichis opposite to or perpendicular to the first direction; a firstdielectric layer arranged between the insulative substrate and the firstupper conductive layer, and surrounding the light-emitting stack; and asecond upper conductive layer arranged on the first upper conductivelayer and the first dielectric layer; a second dielectric layer formedon the first upper conductive layer; and a bonding layer arrangedbetween the lower surface and the insulative substrate, and comprising aside surface, wherein the first dielectric layer has a topmost surfacenot higher than the upper surface of the light-emitting stack in across-sectional view, wherein the first dielectric layer contacts thefirst sidewall, the side surface, and the first upper conductive layer.2. The light-emitting device as claimed in claim 1, wherein the firstupper conductive layer comprises indium tin oxide (ITO), aluminum zincoxide (AZO), cadmium tin oxide, antimony tin oxide, zinc oxide (ZnO),indium zinc oxide (IZO), zinc tin oxide (ZTO), or a combination thereof.3. The light-emitting device as claimed in claim 1, wherein the seconddielectric layer is arranged on the first dielectric layer.
 4. Thelight-emitting device as claimed in claim 1, further comprising anelectrode electrically connected to the bonding layer and arranged onthe insulative substrate.